Read Codex rate limits

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden. It discloses normalization behavior with concrete examples (300 min -> '5h', 10080 min -> 'weekly'), lists the returned fields, and mentions a delegation verdict. While it doesn't detail error behavior or auth requirements, it is transparent enough for a read-only limits check.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two dense sentences with no filler. The first sentence front-loads the operation and return details; the second gives actionable guidance. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a parameterless read tool with no output schema, the description is complete: it explains normalization, names the returned fields, signals read-only intent, and provides usage context. An agent has enough information to invoke and interpret the result correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters and schema coverage is 100%, so there is no parameter information the description needs to add. The baseline for 0-parameter tools is 4, and the description appropriately focuses on output and usage rather than parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Read') and resource ('Codex usage limits'), and details what the tool returns: normalized windows, percentages, reset times, and a delegation verdict. It also distinguishes itself from siblings like codex_delegate by framing this as a pre-flight check.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use the tool: 'Check this before delegating anything large.' This gives clear usage context relative to the delegation workflow, though it does not explicitly name alternatives or provide when-not-to-use cases.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.